Liquid pressure control for refrigeration system



April 15, 1969 J. G LEIMBACH 3,438,217

LIQUID PRESSURE CONTROL FOR REFRIGERATION SYSTEM Filed May 22, 1967 Sheet .1 of 2 FIG. 3

\NVENTDR JOHN GEORGE LEIMBACH April 15, 1969 J. G. LEIMBACH 3,433,217

LIQUID PRESSURE CONTROL FOR REFRIGERATION SYSTEM Filed May 22. 1967 Sheet 2 51"? FIG. 5

INVENTOR JOHN GEORGE LEIMBACH MMMPM United States Patent 3,438,217 LIQUID PRESSURE CONTROL FOR REFRIGERATION SYSTEM John George Leimbach, Crestwood, Mo., assignor to Sporlan Valve Company, St. Louis, Mo., a corporation of Missouri Filed May 22, 1967, Ser. No. 645,845 Int. Cl. F25]: 41/04 US. Cl. 62196 14 Claims ABSTRACT OF THE DISCLOSURE A control device for a refrigeration system in which a condenser valve is located between the compressor discharge and the condenser inlet for regulating flow therebetween in response to a predetermined high side pres sure downstream of the condenser, and in which a by-pass valve is located in a by-pass line that interconnects the compressor discharge with the receiver, the by-pass valve communicating with the compressor discharge upstream of the condenser valve and opening at a predetermined pressure differential between the pressure upstream from the condenser valve and the pressure downstream of the by-pass valve.

Background 0 the invention This invention relates generally to improvements in a liquid pressure control for a refrigeration system, and more particularly to a control for maintaining a minimum liquid pressure in the liquid receiver during periods of low condensing ambients.

The maintenance of a minimum liquid pressure in the receiver is accomplished by diverting -a portion of the discharge gas directly to the receiver, thus increasing the pressure of the liquid in the receiver. This pressure increase prevents the refrigerant from draining out of the condenser. Consequently, the condenser is flooded until its eflective surface is reduced. Once the condenser is partially flooded, the condenser pressure is raised to equal the receiver pressure, and the refrigerant flows from the condenser to the receiver at a predetermined high pressure. This effect is well known and is disclosed in US. Patent No. 1,790,237, issued Jan. 27, 1931.

Several different valve arrangements have been used to achieve this result, but each has disadvantages. For example, one arrangement includes a valve in the line from the compressor to the condenser, and another valve in the by-pass line. This method does enable the closing off of flow to the condenser which is necessary to achieve the desired receiver pressure quickly on start-up of the system. A valve arrangement that causes the condenser to flood by preventing flow from the condenser to the receiver does not provide a comparable fast build-up of receiver pressure.

However, the valve arrangement using two control valves as described above have several important disadvantages. (1) The valve in the line from the compressor to condenser controls on condenser inlet pressure and must be set to open at a desired inlet pressure. The valve in the by-pass line controls the condenser outlet pressure and must be set to open at a desired minimum receiver pressure. Setting the two valves and maintaining the appropriate relation between the two settings is diflicult to attain in the field. (2) Because the reciprocating compressor delivers the gas to the condenser inpulses (a pulse occurring with each piston stroke), a valve that senses this condenser inlet or compressor discharge pressure is subjected to these pulsations. The pulsations reduce the life of the valves flexible motor element. (3) Changes in the pressure drop across some valves that are not of 3,438,217 Patented Apr. 15, 1969 the balanced port design affect the setting of the valves. (4) The piping connection between two valves is expensive.

Another valve arrangement in which the condenser inlet and the by-pass line are valved off is disclosed in US. Patent No. 3,149,475, issued Sept. 22, 1964 and owned by the common assignee of the present application. The three-way valve of this arrangement has a disadvantage in that the valve member must move through its full stroke to achieve the opening of one port and the complete closing of the other port. Because of the high gradient inherent in such valves, a large pressure change is needed to accomplish this result. Consequently, a three-way valve of this type does not control the desired receiver pressure accurately.

The present control means provides the desired results of closing ofl regulating flow to the condenser inlet and of regulating the flow through the bypass line without the disadvantages of the previous valve arrangements.

Summary of the invention A pressure-responsive means is operatively connected to the condenser valve means located between the compressor discharge and the condenser inlet, and is in communication with the high side of the system downstream of the condenser. The pressure-responsive means opens the condenser valve means at a predetermined high side pressure downstream of the condenser. A by-pass valve means is disposed in the bypass line and communicates with the compressor discharge upstream of the condenser valve means, the by-pass valve means opening at a predetermined pressure diflerential between the pressure upstream from the condenser valve means and the pressure downstream of the by-pass valve means.

Specifically, the pressure-responsive means is in communication with the receiver and opens the condenser valve means at a predetermined receiver pressure, and the by-pass valve means opens at a predetermined pressure diflerential, and is a check valve.

The motor element of the pressure-responsive means is located in a chamber subjected to the high side pressure downstream of the condenser, and operates in response to such high side pressure to move the piston toward or away from the condenser inlet port to regulate the flow therethrough. The motor element is isolated from the compressor pulsations.

Moreover, the piston in the condenser valve means is pressure-balanced, and therefore, does not transmit any compressor pulsations to the motor element operatively connected to the piston.

The condenser valve means and the by-pass pressure diflerential and check valve means are combined into a single control unit, but provide two separate and independent valve ports. The condenser inlet port opens on an increase in pressure in the isolated bellows chamber, and the by-pass port opens when the pressure in the valve body upstream of the condenser inlet port is higher, by a. predetermined amount, than the pressure downstream of the by-pass port.

The by-pass pressure differential and check valve means includes a stem, a valve member carried by the stem for opening and closing the by-pass port, and a guide means on the piston of the condenser valve means which engages and guides the stem during stem movement.

A retardation means engages the stem and exerts a controlled amount of drag to slow closing movement of the stem and valve member to preclude flutter. The retardation means includes a shoulder fixed adjacent to the stem, and a wedge urged frictionally between the stem and shoulder.

Brief description of the drawing FIG. 1 is a cross-sectional view of the control means;

FIG. 2 is a diagrammatic view of a system utilizing the control means of FIG. 1;

FIG. 3 is a diagrammatic vieW of a modified refrigeration system utilizing the control means;

FIG. 4 is a diagrammatic view of another modified refrigeration system utilizing the control means, and

FIG. 5 is a diagrammatic view of another modified refrigeration system utilizing the control means.

Description of the preferred embodiments Referring now by characters of reference to the drawing, and first to FIG. 1, it will be understood that the control device 9 for the refrigeration system includes an elongate body 10 housing both the condenser valve means and the by-pass pressure differential and check valve means.

The condenser valve means includes an internal passage 11 having an inlet 12 adapted to be connected to the compressor discharge, and having an outlet 13 adapted to be connected to the condenser inlet. Located within the body 10 and in the passage 11 is a relatively transverse seating ring 14, the seating ring 14 being located at the outlet 13 of the passage 11.

Slidably mounted within the body passage 11 is a cupshaped piston 15. The piston 15 is movable in a direction along a longitudinal axis in the body passage 11. The body 10 has an internal cylinder portion 16 that closely, yet slidably, engages the side wall of the piston 15 during piston movement. The open end of the piston 15 carries a seating ring 17 that is movable toward or away from the fixed seating ring 14 to define and regulate the opening of a peripheral condenser inlet port 20. The condenser inlet port 20 opens transversely, or in a plane perpendicular, to the longitudinal axis of movement of piston 15.

A plurality of transverse openings 21 are located in the side wall of piston 15, the transverse openings 21 communicating with the passage inlet 12. Consequently, opposite sides of the piston 17 are subjected to the same pressure located upstream of the condenser inlet port 20, thereby providing a pressure-balanced piston 15. For reasons which will later appear, a compression spring 22 is located within and engages the piston 15, the compression spring 22 tending to urge the piston 15 in a direction so as to open the condenser inlet port.

A pressure-responsive means is provided to actuate the piston 15 and regulate refrigerant flow through the condenser inlet port 20. This pressure-responsive means includes a chamber 23 in the body 10 and separated from the passage 11 by a transverse body partition 24. Fixed within the chamber 24 is a bellows 25, constituting a flexible motor element. One end of bellows 25 is carried by a collar 26 fixed to the body 10. The opposite end of the bellows 25 is carried by a nut 27 threadedly attached to and carried by one end of a push rod 30. The push rod 30 slidably extends through the partition 24 and into the body passage 11. The other end of push rod 30 is provided with a head 31 seating on the closed end of piston 15. The compression spring 22 keeps the closed end of piston 15 in contact with the push rod head 31 at all times.

Fixed to the body 10 is an elongate, tubular housing 32, the housing 32 being closed at its end by a seal cap 33. Located within the housing 32 is a compression spring 34, one end of the spring 34 engaging the bellows nut 27 and the opposite end engaging an adjusting nut 35 threadedly connected to and located within the housing 32. The compression spring 34 tends to expand the bellows 25, and tends to urge the piston 15, through the push rod 30, in a direction to close the condenser inlet port 20.

Located within the spring housing 32 and below the adjusting nut 35, is a tubular sleeve 36. The sleeve 36 has a flange 37 disposed between and held by the collar 26 and spring housing 32. Inward, threaded movement of the adjusting nut 35 is limited by engagement of the nut 35 with the end of the sleeve 36, the sleeve 36 constituting a stop that limits the compression of spring 34 and acts as a guide for the spring.

A passage 40 in the body 10 places the chamber 23 in communication with some part of the high side of the refrigeration system, as for example with the receiver, as will be later explained. It will be understood that the outside surface of bellows 25 is subjected to the receiver pressure, and that the bellows 25 expands and contracts responsive to variations in the receiver pressure.

The by-pass pressure diiferential and check valve means includes a valve housing 41 fixed to the lower end of body 10, the upper end of the valve housing 41 providing the seating ring 14 partially defining the condenser inlet port 20. Located within and threadedly connected to the valve housing 41 is tube 42 defining a valve seat 43. Extending axially through the tube 42 and longitudinally of the body passage 11 is an elongate stem 44. Formed with the stem 44 is a conical or upwardly tapered head 45. Slidably mounted on the stem 44 above the conical head 45 is a disc 46 constituting a valve element, the disc cooperating with the valve seat 43 to define the valve port.

The valve disc 46 can tilt on the conical head 45, if necessary to accommodate an inclination of seat 43, to effect a tight seal with the valve seat 43. A small compression spring 47 is disposed about the stem 44, one end of the spring 47 engaging the valve disc 46 and the opposite end engaging a lock ring 50 fixed to the stem 44. The spring 47 tends to hold the valve disc 46 tightly against the conical stem head yet enables relative tilting during seating, if required.

The upper end 52 of stem 44 extends into the cupshaped piston 15. Formed inside of the piston 15 integral with the end wall, is a projecting guide tube 51. The stem end 52 is slidably received within the guide tube 51, and consequently, the axial movement of stem 44 is constrained and guided independent of any axial movement of the cup-shaped piston 15.

A valve housing 41 extends below the internal tube 42, and is provided with a closed end 53. The sides of the valve housing 41 are provided with a plurality of openings 54 below the valve disc 46 to place the valve port defined by seat 43 and disc 46 in communication with the peripheral space 55 formed between the valve housing 41 and a tubular connection 56 leading to the receiver.

The housing end 53 is provided with an opening 57 defined by a conical or downwardly tapered shoulder 57 through which the opposite end of the stem 44 extends. Fitted over the lower stem end is a conical or downwardly tapered wedge 60 preferably constructed of a material such as Teflon. The wedge 60 is split longitudinally to enable expansion and contraction, and is located between and engages the conical shoulder 57 and the stem 44. A compression spring 61, located about the stem 44 and between the conical head 45 and the Teflon wedge 60, tends to urge the Teflon wedge 60 into the opening defined by the conical shoulder 57. This spring 61 determines the frictional drag exerted by the Teflon wedge 60 on the valve stem 44. The frictional drag of the Teflon Wedge 60 prevents vibration or flutter of the stem 44 and hence of the valve disc 46.

Another spring 62 located about the stem 44 and located between the conical head 45 the closed housing end 53, tends to urge the valve disc 46 in a direction toward and against the valve seat 43, thereby providing the spring-loaded check valve feature to the by-pass pressure differential and check valve means.

The refrigeration system disclosed in FIG. 2 illustrates one usage of the control device previously described. As is usual in a system of this type, the system includes a compressor 63 having a discharge line 64 connected to the inlet 12 of ,the liquid pressure control device 9. The outlet 13 of the control device 9 is connected by line 65 to the inlet of condenser 66. The outlet of the condenser 66 is connected through a line 68 .to a receiver 70. As is usual, the receiver 70 is connected operatively through an expansion valve 71 to the evaporator 72, and thence through suction line 73 to the compressor 63. The pressure tubing 74 connects the passage 40 of the control device 9 directly to the receiver 70 so that the chamber 23 is subjected to receiver pressure. A by-pass line 75 connects the compressor discharge line 64 to the receiver 70 through the control device 9.

During summer operation, the condenser pressure is high. The force exerted by the compression spring 34 on the bellows 25 directly opposes the force exerted on the opposite side of the bellows 25 by the receiver pressure in chamber 23. The high receiver pressure in chamber 23 will keep the bellows 25 collapsed. Consequently, the cupshaped piston 15 will raise to open the condenser inlet port 20, the spring 22 maintaining the closed end of the piston 15 in contact with the push rod head 31. The condenser inlet port will open at a predetermined receiver pressure exerted on the bellows 25. Whenever the receiver pressure is high, as during summer operation, the condenser inlet port 20 will be fully opened.

The valve disc 46 is set to open at a predetermined pressure differential between the pressure in the passage 11 upstream of the by-pass valve port and the pressure in the by-pass line 75. This pressure differential is obtained only when the condenser inlet port has restricted flow to the condenser.

In winter or at times when the temperature of the condenser ambient is relatively low, it will be understood that the condenser pressure and the receiver pressure drop in proportion to the outside temperature. When the temperature drops to a predetermined point, the receiver pressure in the chamber 23 lowers, and the force exerted by the internal spring 34 expands the bellows 25. Upon expansion of the bellows 25, the piston 15 will lower and the seating ring 17 will begin to throttle the condenser inlet port 20 leading to the condenser 66. The valve disc 46 will not open until the predetermined pressure differential is reached. Movement of the piston 15 is independent of operation of the valve stem 44 and the valve disc 46.

When the condenser inlet port 20 is throttled, a point is reached where the pressure drop across the condenser inlet port 20 and across the condenser 66 will cause pressure above the valve disc 46 to rise where the pressure differential will cause the valve disc 46 to open the bypass port. The important matter is not the specific values of pressure on opposite sides of the valve disc 46, but that the differential value between the compressor discharge pressure and the receiver pressure reaches a predetermined value at which point the valve disc 46 opens the by-pass port. When the valve disc 46 starts to open ,the by-pass port, gas flows to the receiver 70 and causes a build-up in receiver pressure. As a result the receiver pressure in the chamber 23 will increase, and the bellows 25 will contract to allow the piston 15 to raise and open the condenser inlet valve 20. The piston 15 thereby causes a modulation of the condenser inlet port 20 to maintain a certain receiver pressure.

As the condenser ambient becomes colder, more gas must be by-passed to the receiver 70. The bellows 25, under these circumstances, causes further closing of the condenser inlet port 20, which in turn, causes the valve disc 46 to open further to bypass more gas.

To start the refrigeration system, the receiver pressure must be built up quickly. The condenser inlet port 20 is completely closed because of the reduced receiver pressure. The compressor '63 pumps all of the gas from its discharge through the by-pass port, defined by the valve disc 46 and seat 43, directly into the receiver 70. Consequently, the receiver pressure is built up quickly, and at a predetermined value will cause the bellows 25 to collapse to such an extent that the piston 15 will raise and open the condenser inlet port 20 to permit flow of the gas to the inlet of condenser 66. The refrigerant How will then be divided between the condenser inlet port 20 and the valve port. The condenser inlet port 20 will then modulate to maintain the desired receiver pressure as previously described.

When the system is shut down, the valve disc 46 will close the by-pass port and the receiver pressure dro s. The condenser inlet port 20 will then be completely closed.

Because the bellows 25 is located in a chamber 23 isolated from the compressor discharge and subjected only to the receiver pressure, and because the piston 15 is completely pressure-balanced, the bellows 25 is not subjected to compressor pulsations either directly or through the push rod 30.

Because the valve stem 44 is subjected to a controlled frictional drag exerted by the Teflon wedge 60, the valve disc 46 will not vibrate or flutter in response to minor varia ns in pressure differential.

In order to achieve a rapid build-up of pressure in the receiver at the start-up of the refrigeration system, it is necessary in the system shown in full lines in FIG. 2, to install a conventional check valve 67 in the line from the condenser 66 to the receiver 70. This check valve 67 prevents any fiow of gas into the condenser outlet.

The check valve 67 can be eliminated in the system of FIG. 2 provided that the line, as illustrated by line 68 in FIG. 4 is installed from the condenser outlet to the receiver 70 at a location below the liquid level in the receiver 70 so that when the discharge gas is diverted to the receiver 70, liquid is forced up into the condenser 66. Because liquid flowing into the condenser 66 would fill it in a short time, it is then possible to build the liquid pressure up rapidly without the use of the check valve 67. Therefore, the use of the check valve 67 is optional depending ont he piping from the condenser 66 to the receiver 70.

The pressure-balanced valve piston 15 eliminates the effect of unbalanced pressure across the condenser inlet port 20, thereby allowing a small diameter, long stroke bellows 25 to control the receiver pressure accurately regardless of the pressure drop across the condenser inlet port 20.

It is also possible to connect the bellows chamber 23 to the condenser drain line because compressor pulsations are normally diminished by the time the refrigerant travels through the condenser 66. It would be desirable in some installations to use this location. Such as instance might exist when the complete control device 9 is installed by a manufacturer of condensers, and the condenser was applied in the field to a system whose receiver is located a long distance from the condenser. In such a case, as represented by the system disclosed in FIG. 3, the bypass line could be installed at the same location, or in other words, at the condenser outlet, downstream of the check valve 67 Still another alternate location for the line from the bellows chamber 23 is a connection with the liquid line downstream of the receiver 70, as is indicated by the line 74 in FIG. 5.

The frictional drag exerted on the valve stem 44 exerts a specific drag on the stem 44, and hence on the valve disc 46 to prevent the disc 46 from pulsating. Springloaded valves are characterized by a tendency to flutter even when subjected to a non-pulsating flow. With the additional problem of applying such a valve in a line with compressor pulsation, it is essential that some means be employed to prevent the valve disc 46 from vibrating violently. The frictional wedge 60 solves this problem.

The slight leakage of refrigerant past the balanced valve piston where it slides in its body cylinder portion 16, and past the valve disc 46 where it touches the conical head 45, is negligible. The location of the bypass valve means inside of the same valve body 10 with the condenser valve means provides for a more compact and less expensive construction.

I claim as my invention:

1. A control means for a refrigeration system including a condenser having an inlet and an outlet, a receiver connected with the condenser outlet, a evaporator connected with the receiver, an expansion means at the inlet to the evaporator, a compressor having an intake and a discharge, the compressor intake being connected to the evaporator, and a by-pass line interconnecting the compressor discharge with the receiver, the improvement comprising:

(a) a condenser valve means between the compressor discharge and the condenser inlet and regulating flow therebetween,

(b) a pressure-responsive means operatively connected to the condenser valve means and in communication with the high side of the system downstream of the condenser, the pressure-responsive means opening the condenser valve means at a predetermined high side pressure downstream of the condenser, and

(c) a by-pass valve means in the by-pass line and communicating with the compressor discharge upstream of the condenser valve means, the by-pass valve means being spring-loaded and closing the bypass line and opening at a predetermined pressure differential between the pressure upstream from the condenser valve means and the pressure downstream of the by-pass valve means.

2. A control means for a refrigeration system as defined in claim 1, in which:

((1) the condenser valve means includes:

(1) a body having an inlet connected to the compressor discharge and having an outlet con nected to the condenser inlet, the body being provided with a condenser inlet port between the body inlet and outlet, and

(2) a valve element movable toward or away from the condenser port to regulate flow therethrough, and

(e) the pressure-responsive means includes:

(1) a chamber isolated from the flow from body inlet to body outlet and from the pressure of such flow,

(2) means subjecting the chamber only to the high side pressure downstream of the condenser,

( 3) a motor element located in the chamber, and

(4) means operatively connecting the motor element to the valve element for moving the valve element in response to the high side pressure downstream of the condenser.

23. A control means for a refrigeration system including a condenser having an inlet and an outlet, a receiver connected with the condenser outlet, an evaporator connected with the receiver, an expansion means at the inlet to the evaporator, a compressor having an intake and a discharge, the compressor intake being connected to the evaporator, and a by-pass line interconnecting the compressor discharge with the receiver, the improvement comprising:

(a) a condenser valve means between the compressor discharge and the condenser inlet and regulating flow therebetween,

(b) a pressure-responsive means operatively connected to the condenser valve means and in communication with the high side of the system downstream of the condenser, the pressure-responsive means opening the condenser valve means at a predetermined high side pressure downstream of the condenser, and

(c) a by-pass valve means in the by-pass line and communicating with the compressor discharge upstream of the condenser valve means, the by-pass valve means opening at a predetermined pressure differential between the pressure upstream from the condenser valve means and the pressure downstream of the by-pass valve means,

(d) the bypass valve means being a check valve means.

4. A control means for a refrigeration system including a condenser having an inlet and an outlet, a receiver con nected with the condenser outlet, an evaporator connected with the receiver, an expansion means at the inlet to the evaporator, a compressor having an intake and a discharge, the compressor intake being connected to the evaporator, and a by-pass line interconnecting the compressor discharge with the receiver, the improvement comprising:

(a) a condenser valve means between the compressor discharge and the condenser inlet and regulating flow therebetween,

(b) a pressure-responsive means operatively connected to the condenser valve means and in communication with the high side of the system downstream of the condenser, the pressure-responsive means opening the condenser valve means at a predetermined high side pressure downstream of the condenser, and,

(c) a by-pass valve means in the by-pass line and communicating with the compressor discharge upstream of the condenser valve means, the by-pass valve means opening at a predetermined pressure differential between the pressure upstream from the condenser valve means and the pressure downstream of the by-pass valve means,

((1) the condenser valve means including:

( 1) a body having a passage therethrough connected to the compressor discharge and the condenser inlet,

(2) a substantially cup-shaped piston movable in the passage along an axis, the piston having a transverse opening that subjects opposite sides of the piston to the same pressure in the passage so as to be pressure-balanced, and the piston carrying a peripheral seating ring,

(3) means in the passage providing a peripheral seating ring coacting with the piston ring to provide a condenser inlet port opening transverse to the piston axis, the piston being movable to regulate flow through the condenser inlet port, and to the condenser, and

(e) the pressure-responsive means including:

(1) a chamber subjected to the high side pressure downstream of the condenser,

(2) a motor element in the chambers subjected to the high side pressure, and

(3) means operatively connecting the motor element with the piston for moving the piston in response to the high side pressure.

5. A control means for a refrigeration system including a condenser having an inlet and an outlet, a receiver connected with the condenser outlet, an evaporator connected with the receiver, an expansion means at the inlet to the evaporator, a compressor having an intake and a discharge, the compressor intake being connected to the evaporator, and a by-pass line interconnecting the compressor, discharge with the receiver, the improvement comprising:

(a) a condenser valve means between the compressor discharge and the condenser inlet and regulating flow therebetween,

(b) a pressure-responsive means operatively connected to the condenser valve means and in communication with the high side of the system downstream of the condenser, the pressure-responsive means opening the condenser valve means at a predetermined high side pressure downstream of the condenser, and,

(c) a by-pass valve means in the by-pass line and communicating with the compressor discharge upstream of the condenser valve means, the by-pass valve means opening at a predetermined pressure differential between the pressure upstream from the condenser valve means and the pressure downstream of the 'by-pass valve means,

(d) the condenser valve means including:

(1) a body having a passage therethrough connected to the compressor discharge and the condenser inlet, the body being provided with a condenser inlet port in the passage, and

(2) a piston regulating flow through the condenser inlet port, the piston and condenser inlet port being arranged to provide a pressure-balanced piston,

(e) the pressure-responsive means including:

(1) a chamber subjected to the high side pressure downstream of the condenser,

(2) a motor element in the chamber subjected to the high side pressure,

(3) means operatively connecting the motor element with the piston for moving the piston in response to the high side pressure, and

(f) the by-pass valve means including:

(1) means providing a by-pass port communicating the by-pass line with the body passage on the upstream side of the condenser inlet port, and

(2) a check valve means closing the by-pass port, the check valve means opening the by-pass port at the predetermined pressure difierential.

6. A control means for a refrigeration system as defined in claim 5, in which:

(g) the check valve means includes:

(1) a stem,

(2) a valve member carried by the stem for opening and closing the by-pass port, and

(3) guide means on the piston engaging and guiding the stem during movement.

7. A control means for a refrigeration system as defined in claim 5, in which:

(g) the check valve means includes:

(1) a stem,

(2) a valve member carried by the stem for opening and closing the by-pass port, and

( 3) a retardation means engaging the stem to slow movement of the stem and valve member to preclude flutter.

8. A control means for a refrigeration system as defined in claim 5, in which:

(g) the check valve means includes:

(1) a stem,

(2) a valve member carried by the stem for opening and closing the by-pass port,

( 3) a shoulder fixed adjacent to the stem, and

(4) a wedge urged between the stem and shoulder to slow movement of the stem and valve member to preclude flutter.

9. A control means for a refrigeration system as defined in claim 8 in which:

(h) the shoulder fixed adjacent to the stem is conical and is located peripherally about the stem, and

(i) the wedge is a compatible cone slidably engaged by the stem, the cone being split, and being urged frictionally between the stem and conical shoulder.

10. A control means for a refrigeration system as defined in claim 5, in which:

(g) the check valve means includes:

(1) a stem,

(2) a valve member carried by the stem for opening and closing the by-pass port,

(3) a first guide means on the piston engaging and guiding one end of the stem during stem movement,

(4) a second guide means engaging and guiding the other end of the stem, and

(5) a retardation means engaging the stem to slow movement of the stem and valve member to preclude flutter.

11. A control means for a refrigeration system including a condenser having an inlet and an outlet, a receiver connected with the condenser outlet, an evaporator connected with the receiver, an expansion means at the inlet to the evaporator, a compressor having an intake and a discharge, the compressor intake being connected to the evaporator, and a by-pass line interconnecting the compressor, discharge with the receiver, the improvement comprising:

(a) a condenser valve means between the compressor discharge and the condenser inlet and regulating flow therebetween,

(b) a pressure-responsive means operatively connected to the condenser valve means and in communication with the high side of the system downstream of the condenser, the pressure-responsive means opening the condenser valve means at a predetermined high side pressure downstream of the condenser, and,

(c) a by-pass valve means in the by-pass line and communicating with the compressor discharge upstream of the condenser valve means, the by-pass valve means opening at a predtermined pressure dif ferential between the pressure upstream from the condenser valve means and the pressure downstream of the by-pass valve means,

(d) the condenser valve means including:

(1) a body having a passage therethrough connected to the compressor discharge and the condenser inlet,

(2) a substantially cup-shaped piston movable in the passage along an axis, the piston having transverse openings to subject opposite sides of the piston to the same pressure in the passage so as to be pressure-balanced, the piston having a peripheral seating ring,

(3) means in the passage providing a peripheral seating ring coacting with the piston ring to provide a condenser inlet port opening transverse to the piston axis, the piston being movable to regulate flow through the condenser inlet port and through the condenser,

(e) the pressure-responsive means including:

(1) a chamber subjected to the high-side pressure downstream of the condenser,

(2) a motor element in the chamber subjected to the high-side pressure, and

(3) means operatively connecting the motor element with the piston for moving the piston in response to the high side pressure, and

(f) the by-pass valve means including:

(1) means providing a by-pass port communicating the by-pass line with the body passage on thed upstream side of the condenser inlet port, an

(2) a check valve means closing the lay-pass port and opening the by-pass port at the predetermined pressure differential.

12. A control means for a refrigeration system as defined in claim 11, in which? (g) the check valve means includes:

(1) a stem extending into the cup-shaped piston,

(2) a valve member carried by the stem for opening and closing the by-pass port, and

(3) a guide means on the inside of the cup-shaped piston slidably receiving one end of the stem for guiding the stem and valve member during movement.

13. A control means for a refrigeration system including a condenser having an inlet and an outlet, a receiver 75 connected with the condenser outlet, an evaporator counected with the receiver, an expansion means at the inlet to the evaporator, a compressor having an intake and a discharge, the compressor intake being connected to the evaporator, and a by-pass line interconnecting the compressor discharge with the receiver, the improvement comprising:

(a) a condenser valve means between the compressor discharge and the condenser inlet and regulating flow therebetween,

(b) a pressure-responsive means operatively connected to the condenser valve means and in communication with the high side of the system downstream of the condenser, the pressure-responsive means opening the condenser valve means at a predetermined high side pressure downstream of the condenser, and

(c) a by-pass valve means in the by-pass line and communicating with the compressor discharge upstream of the condenser valve means, the by-pass valve means opening at a predetermined pressure differential between the pressure upstream from the condenser valve means and the pressure downstream of the by-pass valve means,

(d) the condenser valve means including:

(1) a body having a passage therethrough connected to the compressor discharge and the condenser inlet, the body being provided With a condenser inlet port in the passage, and

(2) a piston regulating flow through the condenser inlet port, the piston and condenser inlet port being arranged to provide a pressure-balanced piston.

(e) the pressure responsive means including:

( 1) a chamber in the body,

(2) means subjecting the chamber to the high- 3 side pressure downstream of the condenser,

(3) a motor element in the chamber having one side subjected to the high-side pressure,

(4) means subjecting the other side of the motor element to a predetermined force in opposition to the high-side pressure, and

(5) means operatively connecting the motor element with the piston for moving the piston in response to the high side pressure,

(f) the by-pass valve including:

(1) means providing a by-pass port communicating the by-pass line with the by-pass passage on the upstream side of the condenser inlet port, and

(2) check valve means closing the by-pass port and opening the by-pass port at the predetermined pressure ditferential.

14. A control means for a refrigeration system as defined in claim 13, in which:

(g) the chamber in the body is isolated from the passage,

(h) the chamber is subjected to the receiver pressure,

(i) one side of the motor element is subjected to the receiver pressure,

(j) the other side of the motor element is subjected to a predetermined force in opposition to the receiver pressure, and

(k) the piston is moved in response to the receiver pressure.

References Cited UNITED STATES PATENTS 3,195,319 7/1965 Wolff.

MEYER PERLIN, Primary Examiner.

US. Cl. X.R. 

